Carrie Underwood and Tony Bennett croon for 'Blue Bloods' -- VIDEO

Tom Selleck should always have a soundtrack when he makes an entrance in a tux!

We’re not sure why Carrie Underwood and Tony Bennett agreed to sing for the second season premiere of CBS’ Blue Bloods on Sept. 23. (Then again, maybe we do: He’s releasing an album called Duets II that comes out for his 85th birthday this month, and it features a duet with blondie herself).

But we’re not going to quibble because A) They sound pretty dang good together and B) Selleck should always have a soundtrack when he makes an entrance in a tux.